Bell Pottinger's allegedly racially divisive work with Oakbay, which is owned by allies of South Africa's president Jacob Zuma, was the subject of a complaint by the opposition party Democratic Alliance, at a hearing on 18 August.

Bell Pottinger has yet to release a statement on Henderson’s resignation, although he told the BBC on Sunday: "Whilst I had no involvement in the account, there were warning signs that I should have heeded. Therefore I must take responsibility."

Succession rumours

It is rumoured that chairman Mark Smith has been made acting CEO with immediate effect, but that Hugh Taggart will be made interim CEO in due course. The business was not able to immediately confirm this.

Lord Bell, co-founder of the business and its chair until August last year, said of Henderson's resignation: "I think it's an empty gesture... it’s called 'I'm taking my bat and going home', it doesn’t solve anything, it just leaves a mess."

Asked whether the case would have wider impacts for the PR industry, he said: "No I don't think so, it's just some local difficulty, it doesn't affect the whole industry."

Sam Burne James also contributed to this report, which was updated with additional comment and details on 4 September